Mersana (MRSN) unusual size buy 7500 August 7.5/12.5 call spreads for $1.05, shares sitting on 200-MA and monthly value low support. The $590M Biotech trades 2X cash with 7% of the float short. Truist started at Buy in November with a $12 target noting several proprietary components in the antibody drug conjugate space seen as very attractive and differentiating and major catalysts coming mid-2023 and 2H23. Baird out in August positive on the co-development deal with GSK alleviating cash concerns. MRSN had a Director buy 316K shares at $3.46/share in May.